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W. 0. PELHAM. RELBASING DEVICE FOR BRAKES 0P DRIVE WHEELS.

No. 586,455. Patented July 13,1897.

INVE TOR WITNESSES Q ATTORNEYS.

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UNITED STATES PATENT OFFICE.

\VALTER O. PELHAM, OF DENISON, TEXAS, ASSIGNOR OF ONE-HALF TO HENRYLOOMIS, OF SAME PLACE.

RELEASING DEVICE FOR BRAKES OF DRIVE-WHEELS.

SPECIFICATION forming part of Letters Patent No. 586,455, dated July 13,1897.

Application filed March 5, 1897.

To all whom it may concern:

Be it known that I, WALTER O. PELHAM, of Denison, in the county ofGrayson and State of Texas, have invented a new and Improved ReleasingDevice for the Brakes of Drive- Wheels, of which the following is afull, clear, and exact description.

The invention relates to a releasing device for fluid-pressureair-brakessuch, for instance, as shown and described in Letters PatentNo. 529,948, granted to me under date of November 27, 1894:.

The object of the present invention is to provide certain new and usefulimprovements in releasing devices for the brakes of drive- Wheels oi":locomotives, whereby the brakes are instantaneously released at the timethe train is in motion and before the braked drive-wheels are on thepoint of sliding on the rails, also before the triple valve acts torelease the brakes, as described and claimed in the patent abovereferred to.

The invention consists of an exhaust device for the brake-pipeindependent of the triple valve and controlled by back pressure in thesteam-chest of the locomotive.

The invention also consists of certain parts I and details andcombinations of the same, as

will be fully described hereinafter and then pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar'characters of reference indicatecorresponding parts in both the figures.

Figure 1 is a side elevation of the improvement as applied, parts of thelocomotive being in section; and Fig. 2 is an enlarged sectional sideelevation of the improvement.

As illustrated in Fig. 1, the brakes A for the drive-wheels B of thelocomotive are connected in the usual manner with the brakecylinder 0,connected by the brake-pipe D with the triple valve E, having connectionwith the train-pipe F, and by the pipe G with the auxiliary reservoir H.

In the brake-pipe D is arranged an exhaust device 0 (shown in detail inFig. 2) and connected by a small pipe P with the steam-chest of thelocomotive-cylinder N, so that back pressure from the steam-chest N canpass Serial No. 626,163. (No model.)

through the pipe-P into the valve-body O of the said exhaust device 0.

The valve-bodyO is preferably made in the shape of a T, having itshorizontal portion interposed in the brake-pipe D, as is plainly shownin the drawings, and in the said body 0 is formed a valve-seat 0 onwhich is normally seated a valve 0 so as to close the brake-pipe to thevertical part of the body 0. The under side of the valve 0 is providedwith a wing 0 adapted to be engaged by the stem 0 of a piston-valve 0adapted to be seated on a seat 0 formed in the lower portion of the body0, and which lower portion is connected with the pipe P. The valve 0 andthe piston-valve O are arranged in such a manner that when the valve 0is held on its seat 0 bygravity or by the action of a spring then thepiston-valve 0 is in a lowermost position, but when a back pressure fromthe steam-chest of the locomotive-engine passes into the pipe P, aspreviously described, then the said piston-valve O is forced upward ontoits seat 0 so that the valve 0 is unseated by the stem 0 engaging andlifting the wing 0 and communication is then established between thebrakepipe D and exhaust-ports 0 formed in the valve-body 0. (See Fig.2.) A vent-pipe 0 leads into the upper end of the piston-valve cylinderto permit the piston-valve O to readily rise and fall in the cylinder.Now it will be seen that by the arrangement described the valve 0 isunseated on back pressure from the steam-chest, so that the air in thebrake-pipe D is exhausted, and consequently the pressure of the air inthe brakecylinder C is reduced, whereby the brakes A are releasedinstantaneously to prevent sliding of the drive-wheels B at the time thetrain is in motion and before the triple valve E is set in action, asdescribed and claimed in the patent previously referred to. Thus it willbe seen that the drive-wheel brakes A are instantaneously releasedwhenever the engineer applies the brakes on the cars and simultaneouslyreverses the engine, as the back pressure from the steam-chest willexert a pressure on the piston-valve O to open the brake-pipe D to theouter air at the ports 0 as previously explained, so that the brakes Aare released instantaneously. It is understood that the exhaust of thebrakepipe pressure through the ports 0 is much quicker than could be hadfrom the release of the triple valve, and hence a quicker release of thebrakes is obtained.

The arrangement shown in the drawings is capable of releasing the brakesof air, steam, or vacuum brake systems, and the only change necessaryfor using it on a vacuum-brake is the employment of a spring ofsufficient strength to hold the valve 0 to its seat 0 while the vacuumis formed in the brake-cylinder O, as otherwise any pressure from thesteam-chest would cause the piston-valve O to be forced up against itsseat and the valve 0 off its seat to release the brakes by admittingair.

It is understood that by the arrangement described the drive-Wheelbrake-release is governed by a fluid-pressure from the steamchest, andthis fluid-pressure is air when the throttle-valve is closed while theengines are being reversed and steam when there is back I pressure inthe cylinders and steam-chest.

The object of releasing the engine-brakes at the time the engine isreversed is to prevent thewheels from sliding on the rails and beinginjured by a flattening of the tires.

Having thus fully described my invention,

I'claim as new and desire to secure by Letters Patent- 1. An automaticdrive-wheel brake-release, provided with an exhaust device, independentof the triple valve, connected with the brake-pipe, and controlled byback pressure in the steam-chest, substantially as shown and described.

2. An automatic drive-wheel brake-release,

\VALTER O. PELHAM.

\Vitnesses:

J. A. CUMMINs, W. J. M RRIN. 7

